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Tuesday, 10 January 2017

Sam Carana on the 5.8 quake in the Canadian Arctic

Sam
Carana reports on yesterday’s earthquake in the Arctic. Since then
there has been another.

Canadian
Arctic Archipelago Hit By M5.8 Earthquake

An
earthquake with a magnitude of 5.8 on the Richter scale hit the
Canadian Arctic Archipelago on January 8, 2017.

Above
image was created with USGS (United States Geological
Survey) content.
The image shows the epicenter of the quake (gold star). The
earthquake hit Barrow Strait on January 8, 2017 at 23:47:12 (UTC),
at 74.320°N 92.305°W and at a depth of 18.9 km.

This
earthquake is important, given its magnitute and given that it hit
an area without large faultlines (though earthquakes are not
uncommon here, also see this
discussion).
Importantly, this earthquake occurred in an area prone to glacial
isostatic adjustment, as illustrated by the image below.

Glacial
isostatic adjustment as
a phenomenon typically takes place over relatively long periods.
Yet, extreme weather events can trigger earthquakes in areas that
are already on the edge.

The extreme weather situation is
depicted by the combination image below.

Similar
to the M4.6
earthquake that hit Baffin Island on
February 12, 2015, this earthquake occurred at a time when surface
temperature anomalies over parts of North America and Greenland were
at the bottom end of the scale. At the same time, temperature
anomalies over the Arctic Ocean are at the top end of the scale, as
illustrated by the left panel in above image. The right panel
in above image shows pressure differences reaching the top and
bottom ends of the scale.

Earthquakes in the Arctic Ocean are
dangerous as they can destabilize methane hydrates. Huge amounts of
methane are present in sediments under the Arctic Ocean in the form
of free gas and hydrates. Earthquakes can send out strong tremors
through the sediment and shockwaves through the water, which can
trigger further earthquakes, landslides and destabilization of
methane hydrates. The situation is especially dangerous when
combined with extreme weather events that can cause cracks and
movement in sediments.

As temperatures in the Arctic keep
rising, the jet streams and polar vortex are changing their shape,
in particular becoming more wavy, which can cause more extreme
weather events such as the events described above.

The
situation is dire and calls for comprehensive and effective action,
as described at the Climate
Plan.